The invention relates to a screen chain conveyor in the form of a screening rod conveyor for root crop harvesting machines that is provided with a belt fastener in the area of at least one of the support belts that receive respective transverse conveying rods, wherein the belt fastener comprises at least one hinge-like articulated connection in the area of connecting members engaging the respective belt ends.
According to DE 1 756 050 U1, a screen conveyor is proposed whose screening rods that are arranged as transverse conveying rods are secured laterally in the area of a belt which is acting as a support belt. The belt ends that are comprised of reinforced belt material are detachably connected to each other by means of a hinge joint wherein a screening rod is acting as a hinge bolt, respectively (similar arrangement: DE 32 46 530 C2). In case of a belt fastener according to DE 1 084 984 A, respective connecting members are also provided in the area of the belt ends. They form the belt fastener by means of a torsionally flexible intermediate member that is fixedly connected to both connecting members. The screw connections provided in this context are not very load-resistant so that the belt fastener in use of the conveyor is subjected to great wear.
According to DE 31 25 310 A1, a screen chain conveyor is proposed in which the belt fastener is provided with an approximately H-shaped intermediate coupling member and the connecting members provided with transverse bores can be connected also by means of the chain rods provided for the system. In a screen chain conveyor according to EP 0 312 629 B1, the belt fastener is designed as a separate hinge whose connecting plates provided with the link eyes engage underneath a free end of the belt, respectively, and secure the belt ends by interacting with a pressure member that is arranged on the topside of the belt. In this way, a comparatively tall belt fastener is provided that is exposed to intensive wear and thus reduces the service life of the conveyor.
In an endless connection for screen rod conveyors according to DE 34 06 333 A1, tabs are provided in the area of the belt ends. They delimit laterally a common connecting element wherein screening rods extend through the latter and the tabs, respectively. A similar construction is disclosed in DE 34 07 167 A1 wherein the respective tabs are provided with widened portions so that improved contact points are defined for the moving conveyor. The construction according to DE 34 29 004 C2 is also provided with an intermediate member that has tabs wherein an additional one of the transverse rods is secured on a connecting bridge in the area of the intermediate member.
In a chain fastener connection that is disclosed in DD 270 648 A1, a separate insertion member is provided in the area of the belt fastener and comprises inwardly projecting parts projecting toward the transverse rods and, in this way, engages the transverse conveying rods. Similar constructions are disclosed in D 270 649 A1 and in DD 272 212 A1 wherein variable embodiments of stud bolts and screw connections are provided, respectively.
In a screening rod according to DE 39 03 921 A1, the belt ends in the area of the connecting members are engaged by respective U-shaped fixtures of metal by means of rivet-like fastening elements. At the free end of the fixtures, meshing webs are formed that serve for receiving a locking bolt. A similar construction is disclosed in DE 297 16 333 U1 wherein this belt fastener in the area of the connecting members has, oppositely positioned relative to each other, a center eye and two lateral eyes which are pivotably connected to each other by a transverse bolt. Accordingly, the connecting members that interact in pairs have conforming connecting profiles meshing with each other and, in the area of the connecting profiles, a respective transverse conveying rod is connected with the connecting members.
In practical use of the afore described prior art belt fasteners on screen chain conveyors for root crop harvesting machines, it has been found that soiling of the components occurring during harvesting operation, in particular in the area of the fastener pairing of the belt fastener, leads to increased wear and the service life of such screen chain conveyors is disadvantageously reduced.
The invention has therefore the object to design a screen chain conveyor for root crop harvesting machines in such a way that at least in the area of the belt fastener that engages the belt ends a reduced wear occurs so that the service life of the system can be extended and, by a simpler repair, a faster return of defective component groups or modules to operation is possible.